Proposed international regulations in the oil pollution area contemplate limiting both the total oil and the rate of oil which can be discharged by a tanker into the ocean. It is likely that these regulations may further require that the tanker be able to prove that it has not discharged oil in the ocean above the prescribed limits. This would require a single device or system to enable the tanker to prove compliance both with total and rate limitations on oil discharges.
It has previously been demonstrated that lipophilic material is feasible for use in adsorbing oil from an oily water stream, and further has been shown that lipophilic material can be analyzed to determine oil concentration, for example, see U.S. Pat. No. 3,612,887, or the Salwico Oil Content Monitor, Salen & Wicander, Sweden, or API Publication No. 4172, 1973, pages 139-144, by Schatzberg and Jackson. None of these prior art devices, however, are capable of monitoring both total oil and rate of oil discharged in an oily water stream. Other prior art disclosures of general interest for measuring oil in water are U.S. Pat. Nos. 3,133,437; 3,167,949; and 3,385,108. These techniques, however, are not capable of measuring low concentrations of oil in water such as may be discharged from a tanker.